Tube containers, such as dispensing tubes, are used to hold and to dispense a wide range of products. These include adhesives, lubricants, lotions, medicants, shampoos, hair dressings, and various oral care products. Some of the lotions, medicants and oral care products contain an antibacterial compound. A problem with such products is that the antibacterial compound may be absorbed or otherwise degraded by the tube materials. The result is that the tube structure needs to be modified to reduce or to eliminate the absorption by the tube structure for the antibacterial compound. In many cases, and especially for oral care products such as toothpaste, it is desirable also to reduce the absorption of the tube structure for other contained substances such as flavors and fragrances. Some package materials absorb flavor and fragrance components in an inappropriate ratio depending on the flavor and fragrance molecules. Thus the flavor or fragrance is changed. This problem needs to be solved for flavors and fragrances to preserve the taste and olfactory properties of the products.
Traditionally, barrier materials have been used to reduce the loss of flavors or fragrances, and in some instances antibacterial compounds. It is widely believed in the industry that a good barrier to flavors and to fragrances is also a good barrier to antibacterial compounds, and that barrier improvement would be similar for all of these organic compounds. The barrier layer is normally selected based on the flavor or fragrance barrier properties. Unfortunately, the traditional belief that a good flavor barrier leads to a good barrier for antibacterial compounds is not accurate. Polymers will have different adsorption affinities for flavors and for antibacterial compounds because of the differences in structure and polarity of these compounds.
Additionally, the shoulder/nozzle portion of the tubes poses issues, for example, with respect to flavor or antibacterial compound loss, because the shoulder and nozzle are relatively thick compared to the remainder of a tube to maintain the mechanical strength of the tube. Further, in order to have good adhesion of the tube body to the shoulder and for cost considerations, polyolefins are usually used as the material for the shoulder/nozzle. The thicker the polymers the greater the absorption. This thickness leads to an unacceptable level of antibacterial compound adsorption. This problem is thought to be solved for flavors by the use of an insert which is a material that has a very low absorptivity for the flavor components. This insert can be formed by an interference fit into the top part of the tube, a film layer onto the inner surface of the tube, or by a layer co-injection molded onto the inner surface of the tube. In these cases, the insert can be disposed on or above a surface of the shoulder/nozzle (i.e., there may be additional laminate layers included). However, the use of inserts requires additional manufacturing steps.
There is a need for dispensing tubes that provide performance equal to or better than existing tubes, but which minimize permeability that reduces the quality of the contents in the tube, and reduces manufacturing costs and operational steps.